NetLogo Vid Extension

The vid extension has a built-in concept of a video source.
At the moment, the only video sources available are movies in the directory the model lives in and cameras attached to the computer.
The vid extension opens a new video source with the vid:<source>-open and vid:<source>-select.
These primitives change the source to the selected source.
If a source is already open, it closes it before opening a new one.

Movie sources are “stopped” after being created by vid:movie-select or vid:movie-open.
Camera sources start off as “playing” after being created by vid:camera-select or vid:camera-open.
If a source is in status “stopped” it can be started with vid:start.
Conversely, if the source is “playing” it can be stopped with vid:stop.
When a source is “stopped”, each call to vid:capture-image will return the same image.

The vid extension also has the concept of a recording, a series of frames which can be sewn into an “mp4” movie.
The recorder status can be queried using vid:recorder-status.
The recorder status is “inactive” until started with vid:start-recorder, which sets it to “recording”.
While the recorder is “recording” the vid:record-view, vid:record-interface, and vid:record-source can be used to save frames to the recording.
You can choose to save the recording while recording using vid:save-recording which saves the movie to the specified file and reset the recording status to “inactive”.
If you would prefer to throw away the recorded frames without saving, use vid:reset-recorder.

vid:movie-select

Prompts the user to select a movie to use as a video source.
The formats supported are those supported by JavaFX2.
This command does not error if the user cancels.
Use vid:status to see if the user selected a movie.

Example:

vid:movie-select

Errors:

Message "vid: format not supported": the user selected a movie with an unsupported format.

vid:movie-open filename

Opens a video from the file system.
If the provided path is not absolute the extension searches for the given path relative to the current model directory.
If the provided path is absolute the extension opens the file.

Example:

vid:movie-open "foo.mp4" ; Opens foo.mp4 in the directory containing the model
vid:movie-open user-file ; Opens a dialog for the user to select a movie
vid:movie-open "/tmp/foo.mp4" ; Opens a movie from the "/tmp" directory

Errors:

Message "vid: no movie found": the movie could not be found.

Message "vid: format not supported": the user selected a movie with an unsupported format.

vid:stop

vid:status

Reports the current status of an active video.
Note that after calling vid:movie-open or vid:movie-select the status will be set to “stopped”,
while after calling vid:camera-open or vid:camera-select the status will be “playing”.

vid:show-player widthheight

Shows a player in a separate window.
If there is no video source, the window will be an empty black frame.
If there is an active video source, it will be displayed in the window with the specified width and height.
If there is a playing video source, it will be displayed in the window at its specified width and height.
If width and height are omitted, the video will be displayed in its native resolution.

Example with native resolution:

vid:show-player

Example with custom resolution:

(vid:show-player 640 480)

Errors:

Message "vid: invalid dimensions": The selected dimensions are invalid (one of the dimensions is zero or negative).

vid:recorder-status

Reports the current status of the recorder.
Initially and after the recorder is saved (via vid:save-recording) or reset (via vid:reset-recorder) the recorder status is “inactive”.
After calling vid:start-recorder the status will be “recording”.

vid:start-recorder

Starts the recorder.
If the recorder is already running this will cause an error to be raised.
If desired, a recording width and height can be supplied.
If width and height are not supplied, they will be determined from the first frame recorded.

Example:

vid:start-recorder
(vid:start-recorder 640 480)

Errors:

Message "vid: recorder already started": The recorder has already been started. The existing recording should be saved or reset before starting the recording.

Message "vid: invalid dimensions": The selected dimensions are invalid (one of the dimensions is zero or negative).

vid:save-recording filename

Saves the recording to the specified path.
If the recorder is not running this will cause an error to be raised.
Note that at present the recording will always be saved in the “mp4” format.
If the supplied filename does not end in “.mp4”, the “.mp4” suffix will be added.
Note that vid:save-recordingwill overwrite existing files of the same name.
vid:save-recording will error if the recorder has not been started or if the file cannot be written since the containing directory does not exist.

Example:

vid:save-recording "foo.mp4" ; Saves to foo.mp4 in the directory containing the model
vid:save-recording user-new-file ; Opens a dialog for the user to select a save path
vid:save-recording "/tmp/foo.mp4" ; Saves the recording to the "/tmp" directory

Errors:

Message "vid: recorder not started": The recorder has not been started. Start the recorder with vid:start-recorder.

Message "vid: no such directory": The directory containing the specified save file does not exist.

Message "vid: no frames recorded": You tried to save a recording with no frames recorded. Check that you are recording properly or use vid:reset-recording to to change the recording format without saving.